Here is an idea, using Speedy Entry Tool. Assuming that you are at the end of a measure, having room for a half note, but wanting a whole note:1. Open the Tuplet Definition dialog box (Windows: Ctrl-1; Mac: Option-1).
2. Define the tuplet as "2 Half(s) in the space of 1 Half(s)". Set "Number" and "Shape" to "Nothing". Click OK.
3. Enter a whole note. The Speedy Entry frame jumps to next measure.
4. Enter a half rest. Hide it (letter 'O' key).
Playback will not be fully correct, because of the rest. If playback is important, switch to MIDI Tool:
1. Doubleclick the measure with the whole note. The MIDI Tool window appears.
2. MIDI Tool menu > Note Durations (shortcut: click the 8th note icon)
3. In the MIDI Tool window, double-click the handle on the whole note. The Edit MIDI Note dialog box appears.
4. Set Stop Time to 2048. Click OK.
Setting Stop Time to 2048 means "a half note later than the notated Stop Time". 2048 = a half note; 1024 = a quarter; 512 = an eighth, a.s.o.
Peter